A new influenza virus strain, H7N9, surfaced this February in China, eliciting swift response and capturing headlines with concern of pandemic. As of May 29, a total of 132 confirmed cases and 37 deaths were reported. International agencies are keeping tight watch, as are China’s neighbors, with China itself deep in the epidemiological hunt, seeking the source of the virus, the mode of transmission, and insights into land use and ecological changes that might contribute to its spread. Laboratory analysis shows that genes from H7N9 are of avian origin.

This is but the most recent in a series of outbreaks of zoonotic diseases — diseases that are transmitted to humans by animals, including mad cow, H5N1, swine flu, SARS and West Nile virus. Of the diseases that have emerged or reemerged since World War II, 75 percent have been zoonotic. Driving up the risk is a global web of changes that are increasing people’s contact with natural environments and with each other — from urbanization and human encroachment on wild habitats, to expanded trade networks and greater personal mobility.

The mounting health challenge of zoonotic disease is “surprising the public, disrupting globalization, resulting in massive economic losses, and jeopardizing business and diplomatic relations,” noted a 2007 Institute of Medicine report. As silver lining, the report also spotlighted a promising approach to addressing the problem that also offers environmental benefits: One Health.

Looking at Linkages

The basic premise of One Health is that environmental, animal and human health are inextricable. The protection of one therefore requires active, coordinated monitoring and protection of all three, including integrated training of health and environmental professionals. “None of the health and environment problems we’re looking at today is solvable by one discipline,” says Steve Osofsky, executive director of wildlife health and health policy at the Wildlife Conservation Society. “And yet as professionals we’re all trained, very much, in a canalized way.”

With collaborators across the world, Osofsky is managing the Health & Ecosystems: Analysis of Linkages program. HEAL, as it’s known, is investing more than $30 million in six distinct One Health research projects, each one designed to improve public health outcomes among some of the world’s poorest people while conserving critical natural areas. Jonathan Patz, for example, a medical doctor at the University of Wisconsin–Madison, is leading an investigation into how deforestation in the Amazon affects the transmission of malaria. The World Wildlife Foundation is heading another project that seeks to understand the connection between marine protected areas and the health of coastal fishing communities. Each of the studies hopes to “robustly document linkages between intact nature and public health,” says Osofsky.

Building on previous iterations of the idea, the Wildlife Conservation Society introduced the natural environment — biodiversity, ecosystem resilience — as a third essential node connecting the health of people and animals.One Health’s push for integrative medicine is not new. The pioneering pathologist Rudolf Virchow stated in 1858, “Between animal and human medicine there is no dividing line — nor should there be.” One of Virchow’s pupils is credited with devising the inclusive term “One Medicine.” But this holistic approach lost currency amid a 20th century drive for specialization. Only in September 2004 did the Wildlife Conservation Society forcefully revive the idea at a conference held under the banner of One World, One Health. There it developed the 12 Manhattan Principles, which appealed to governments and professionals for broad recognition of, and proactive investment in, a global One Health infrastructure. Building on previous iterations of the idea, the Wildlife Conservation Society introduced the natural environment — biodiversity, ecosystem resilience — as a third essential node connecting the health of people and animals.

These principles “laid much of the modern foundation for the One Health movement,” says David Nabarro, who was appointed U.N. senior coordinator for avian and pandemic influenza in 2005.

At that time, Nabarro drew on the newly minted principles to lead the U.N. System Influenza Coordination efforts, which cast a wide net for partners in the prevention of avian and human influenza pandemics. He included experts from the U.N.’s Food and Agriculture Organisation and the World Organisation for Animal Health (OIE) alongside those from the more obviously relevant World Health Organization. Following this high-level application of One Health, the idea gained traction beyond the world of influenza, spreading to national health ministries and nonprofits, the Centers for Disease Control and Prevention and the United Nations Environment Programme, and in a formalized tripartite partnership [pdf] among the WHO, FAO and OIE.

“The whole One Health movement has since become much stronger and has gradually entered into the mainstream,” says Nabarro. “We’re now seeing the value of One Health in food safety, for example, or in the long-term future of livestock rearing around the world.”

Nabarro points to USAID’s Emerging Pandemic Threats program, started in 2009, as one of the most sophisticated applications of One Health. With four complementary branches — Predict, Prevent, Identify, Respond — this program catalogs urban and natural disease hot spots, characterizes human and ecological drivers of disease and funds One Health initiatives worldwide. A project sponsored in Uganda in 2010, for instance, brought together park rangers, wildlife specialists and the ministries of Agriculture and Public Health to subdue an anthrax outbreak in hippopotamuses.

“This program perfectly highlighted why we need a transdisciplinary, One Health approach,” says Mac Farnham, an assistant professor of veterinary medicine at the University of Minnesota who worked on the case. “The wildlife folks are mandated to care for wildlife, human health works to prevent anthrax from moving into people and agriculture wants to prevent the disease from getting into livestock.”

Room for Growth

Despite the gains, there is still bountiful room for growth in the development and, particularly, the application of One Health principles.

Osofsky notes that the training of health professionals remains defined by specialization, and that a more interdisciplinary approach — curricula developed jointly across medical, veterinary and agricultural schools, for instance — is an important next step in making One Health more effective.

“One Health programs should look at all sectors — livestock, the environment, food chains and so forth. They were never meant to be anthropocentric.” — Steve Osofsky“A lot has to do with how we train health professionals,” agrees Farnham. “Currently, it takes quite a bit of added effort to get people from different disciplines together and to develop a common understanding.” In African countries where disease outbreak has remained a chronic problem, Farnham praises the One Health Central and East Africa initiative. Funded by USAID, the program’s 10-year strategic plan aims to strengthen preventive health networks by coordinating research, surveillance and response efforts across universities and academic departments in six African countries.

Even more difficult than educational barriers has been the continuous challenge of hewing lofty One Health concepts to real-world situations. The concepts include important but vague guidelines, such as recognizing that human health programs can greatly contribute to conservation efforts. “The point about the original Manhattan Principles was that they are generic, which means they are broadly applicable,” says Nabarro. “But, at the same time, it also means that they need a lot of work to shoot from generic into action. This shift, from principle to practice to accountability, has been quite demanding.”

The challenge is especially evident in efforts to establish organizational partnerships. In a recent case, a $15 million grant provided to synchronize one country’s avian influenza response withered on the vine when two years of discussion failed to solidify any accord between national agencies. “These institutional arrangements,” says Nabarro, “don’t just grow overnight.” But he remains hopeful that, in time, they will grow.

Osofsky, too, maintains a guarded optimism about the long-term potential for One Health, though he expresses concern that many projects are too narrowly focused on zoonoses. “One Health programs should look at all sectors — livestock, the environment, food chains and so forth. They were never meant to be anthropocentric.”

He also points out the surprisingly low profile of One Health, given the age of the concept and the scale of the threats. “It’s a very well-kept secret,” he says. By growing awareness of the principles of One Health and advancing them in practice, he and many others hope to bring the power of interdisciplinary collaboration and cross-fertilization to creating better solutions to some of the most challenging problems of our time.  View Ensia homepage

UPDATED 06.28.13: This article originally incorrectly identified Steve Osofsky as senior policy advisor for wildlife health at the Wildlife Conservation Society.